Method and apparatus for manufacturing flexible light emitting device

ABSTRACT

According to a flexible light-emitting device production method of the present disclosure, after an intermediate region (30i) and flexible substrate regions (30d) of a plastic film (30) of a multilayer stack (100) are divided from one another, the interface between the flexible substrate regions (30d) and a glass base (10) is irradiated with lift-off light. The multilayer stack (100) is separated into a first portion (110) and a second portion (120) while the multilayer stack (100) is in contact with a stage (212). The first portion (110) includes a plurality of light-emitting devices (1000) which are in contact with the stage (212). The light-emitting devices (1000) include a plurality of functional layer regions (20) and the flexible substrate regions (30d). The second portion (120) includes the glass base (10) and the intermediate region (30i).

TECHNICAL FIELD

The present disclosure relates to a method and apparatus for producing aflexible light-emitting device.

BACKGROUND ART

A typical example of the flexible display includes a film which is madeof a synthetic resin such as polyimide (hereinafter, referred to as“plastic film”), and elements supported by the plastic film, such asTFTs (Thin Film Transistors) and OLEDs (Organic Light Emitting Diodes).The plastic film functions as a flexible substrate. The flexible displayis encapsulated with a gas barrier film (encapsulation film) because anorganic semiconductor layer which is a constituent of the OLED is likelyto deteriorate due to water vapor.

Production of the above-described flexible display is carried out usinga glass base on which a plastic film is formed over the upper surface.The glass base functions as a support (carrier) for keeping the shape ofthe plastic film flat during the production process. TFT devices,light-emitting devices such as OLEDs, a gas barrier film, and the otherconstituents are formed on the plastic film, whereby the structure of aflexible display is realized while it is supported by the glass base.Thereafter, the flexible display is delaminated from the glass base andgains flexibility. The entirety of a portion in which TFT devices andlight-emitting devices such as OLEDs are arrayed can be referred to as“functional layer region”.

According to the prior art, a sheet-like structure including a pluralityof flexible displays is delaminated from a glass base, and thereafter,optical parts and other constituents are mounted to this sheet-likestructure. Thereafter, the sheet-like structure is divided into aplurality of flexible devices. This dividing is realized by, forexample, laser beam irradiation.

Patent Document No. 1 discloses the method of irradiating the interfacebetween each flexible display and the glass base with laser light inorder to strip each flexible display from the glass base (supportingsubstrate). According to the method disclosed in Patent Document No. 1,after irradiation with the lift-off light, respective flexible displaysare divided from one another, and each of the flexible displays isdelaminated from the glass base.

CITATION LIST Patent Literature

Patent Document No. 1: Japanese Laid-Open Patent

SUMMARY OF INVENTION Technical Problem

According to the conventional production method, the dividing by meansof laser beam irradiation is carried out after expensive parts, forexample, encapsulation film, polarizer, and/or heat radiation sheet, aremounted to a sheet-like structure including a plurality of flexibledisplays. Therefore, unnecessary parts divided by laser beamirradiation, i.e., parts which are not to be constituents of a finaldisplay, are quite useless. Also, there is a problem that, after beingdelaminated from the glass base, it is difficult to handle a pluralityof flexible displays which have no rigidity.

Such a problem is not limited to flexible displays which include OLEDsas light-emitting devices but can arise in producing a flexiblelight-emitting device which includes a micro LED (μLED) formed as alight-emitting device using inorganic semiconductor materials.

The present disclosure provides a method and apparatus for producing aflexible light-emitting device which are capable of solving theabove-described problems.

Solution to Problem

A flexible light-emitting device production method of the presentdisclosure includes, in an exemplary embodiment, providing a multilayerstack which has a first surface and a second surface, the multilayerstack including a glass base which defines the first surface, aplurality of functional layer regions each including a TFT layer and alight-emitting device layer, a synthetic resin film provided between theglass base and the plurality of functional layer regions and bound tothe glass base, the synthetic resin film including a plurality offlexible substrate regions respectively supporting the plurality offunctional layer regions and an intermediate region surrounding theplurality of flexible substrate regions, and a protection sheet whichcovers the plurality of functional layer regions and which defines thesecond surface, dividing the intermediate region and respective ones ofthe plurality of flexible substrate regions of the synthetic resin filmfrom one another, irradiating an interface between the plurality offlexible substrate regions of the synthetic resin film and the glassbase with lift-off light, and separating the multilayer stack into afirst portion and a second portion by increasing a distance from a stageto the glass base while the second surface of the multilayer stack iskept in contact with the stage. The first portion of the multilayerstack includes a plurality of light-emitting devices which are incontact with the stage, and the plurality of light-emitting devicesrespectively include the plurality of functional layer regions andinclude the plurality of flexible substrate regions of the syntheticresin film, and the second portion of the multilayer stack includes theglass base and the intermediate region of the synthetic resin film.

In one embodiment, the lift-off light is incoherent light.

In one embodiment, the light-emitting device layer includes a pluralityof arrayed micro LEDs, and the lift-off light is laser light.

In one embodiment, separating the multilayer stack into the firstportion and the second portion is carried out while the stage holds thesecond surface of the multilayer stack.

In one embodiment, irradiating the interface between the plurality offlexible substrate regions of the synthetic resin film and the glassbase with the lift-off light is carried out while the stage holds thesecond surface of the multilayer stack.

In one embodiment, a surface of the stage includes a first region whichis to face the plurality of light-emitting devices and a second regionwhich is to face the intermediate region of the synthetic resin film,and suction in the first region is greater than suction in the secondregion.

In one embodiment, the method further includes, before bringing thesecond surface of the multilayer stack into contact with the stage,placing a suction sheet on the stage, the suction sheet having aplurality of openings, wherein the stage includes a porous plate onwhich the suction sheet is to be placed, and the suction sheet includesa first region which is to be in contact with the plurality oflight-emitting devices and a second region which is to face theintermediate region of the synthetic resin film, an aperture ratio ofthe first region being higher than an aperture ratio of the secondregion.

In one embodiment, the method further includes, after separating themultilayer stack into the first portion and the second portion,sequentially or concurrently performing a process on the plurality oflight-emitting devices which are in contact with the stage.

In one embodiment, the method further includes, after separating themultilayer stack into the first portion and the second portion, adheringanother protection sheet to the plurality of light-emitting deviceswhich are in contact with the stage.

In one embodiment, the method further includes detaching from the stagethe plurality of light-emitting devices which are bound to the anotherprotection sheet.

In one embodiment, the method further includes sequentially orconcurrently performing a process on the plurality of light-emittingdevices which are bound to the another protection sheet.

In one embodiment, the process includes attaching a dielectric and/orelectrically-conductive film to each of the plurality of light-emittingdevices.

In one embodiment, the process includes cleaning or etching each of theplurality of light-emitting devices.

In one embodiment, the process includes mounting an optical part and/oran electronic part to each of the plurality of light-emitting devices.

In one embodiment, the process includes cleaning or etching each of theplurality of light-emitting devices.

A flexible light-emitting device production apparatus of the presentdisclosure includes, in an exemplary embodiment, a stage for supportinga multilayer stack which has a first surface and a second surface, themultilayer stack including a glass base which defines the first surface,a plurality of functional layer regions each including a TFT layer and alight-emitting device layer, a synthetic resin film provided between theglass base and the plurality of functional layer regions and bound tothe glass base, the synthetic resin film including a plurality offlexible substrate regions respectively supporting the plurality offunctional layer regions and an intermediate region surrounding theplurality of flexible substrate regions, and a protection sheet whichcovers the plurality of functional layer regions and which defines thesecond surface, the intermediate region and respective ones of theplurality of flexible substrate regions of the synthetic resin filmbeing divided from one another, a lift-off light irradiation unit forirradiating with lift-off light an interface between the plurality offlexible substrate regions of the synthetic resin film and the glassbase in the multilayer stack supported by the stage; and an actuator forincreasing a distance from the stage to the glass base while the stageholds the second surface of the multilayer stack by suction, therebyseparating the multilayer stack into a first portion and a secondportion. The first portion of the multilayer stack includes a pluralityof light-emitting devices adhered by suction to the stage, and theplurality of light-emitting devices respectively include the pluralityof functional layer regions and include the plurality of flexiblesubstrate regions of the synthetic resin film, and the second portion ofthe multilayer stack includes the glass base and the intermediate regionof the synthetic resin film.

In one embodiment, the lift-off light irradiation unit comprises anincoherent light source for emitting the lift-off light.

In one embodiment, the light-emitting device layer includes a pluralityof arrayed micro LEDs, and the lift-off light irradiation unit comprisesa semiconductor laser device for emitting the lift-off light.

In one embodiment, the surface of the stage includes a first regionwhich is to face the plurality of light-emitting devices and a secondregion which is to face the intermediate region of the synthetic resinfilm, and suction in the first region is greater than suction in thesecond region.

In one embodiment, the stage includes a porous plate, and a suctionsheet placed on the porous plate, the suction sheet having a pluralityof openings, and the suction sheet includes a first region which is tobe in contact with the plurality of light-emitting devices and a secondregion which is to face the intermediate region of the synthetic resinfilm, an aperture ratio of the first region being higher than anaperture ratio of the second region.

A suction sheet of the present disclosure is, in an exemplaryembodiment, a suction sheet for use in the above-described productionapparatus, the suction sheet including, a first region which is to be incontact with the plurality of light-emitting devices, and a secondregion which is to face the intermediate region of the synthetic resinfilm, wherein an aperture ratio of the first region is higher than anaperture ratio of the second region.

Advantageous Effects of Invention

According to an embodiment of the present invention, a novel method forproducing a flexible light-emitting device which is capable of solvingthe above-described problems is provided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a plan view showing a configuration example of a multilayerstack used in a flexible light-emitting device production method of thepresent disclosure.

FIG. 1B is a cross-sectional view of the multilayer stack taken alongline B-B of FIG. 1A.

FIG. 1C is a cross-sectional view showing another example of themultilayer stack.

FIG. 1D is a cross-sectional view showing still another example of themultilayer stack.

FIG. 2 is a cross-sectional view schematically showing the dividingpositions in the multilayer stack.

FIG. 3A is a diagram schematically showing a state immediately before astage supports a multilayer stack.

FIG. 3B is a diagram schematically showing a state where the stagesupports the multilayer stack.

FIG. 3C is a diagram schematically showing that the interface between aglass base and a plastic film of the multilayer stack with lift-offlight in the shape of a line.

FIG. 4A is a perspective view schematically showing irradiation of themultilayer stack with a line beam emitted from a line beam source of adelaminating apparatus.

FIG. 4B is a diagram schematically showing the position of the stage atthe start of irradiation with lift-off light.

FIG. 4C is a diagram schematically showing the position of the stage atthe end of irradiation with lift-off light.

FIG. 5A is a cross-sectional view schematically showing the multilayerstack before the multilayer stack is separated into the first portionand the second portion after irradiation with lift-off light.

FIG. 5B is a cross-sectional view schematically showing the multilayerstack separated into the first portion and the second portion.

FIG. 6 is a perspective view showing the glass base separated from themultilayer stack by the delaminating apparatus.

FIG. 7 is a perspective view schematically showing a surface of thestage.

FIG. 8 is a plan view schematically showing the surface of the stage.

FIG. 9A is a schematic diagram enlargedly showing a portion in thevicinity of the boundary between a first region and a second region ofthe surface in a configuration example of the stage.

FIG. 9B is a cross-sectional view taken along line B-B of FIG. 9A.

FIG. 10 is a plan view showing the surface in another configurationexample of the stage.

FIG. 11A is a schematic diagram enlargedly showing a portion in thevicinity of the boundary between a first region and a second region ofthe surface in still another configuration example of the stage.

FIG. 11B is a cross-sectional view taken along line B-B of FIG. 11A.

FIG. 12A is a schematic diagram enlargedly showing a portion in thevicinity of the boundary between a first region and a second region ofthe surface in another configuration example of the stage.

FIG. 12B is a cross-sectional view taken along line B-B of FIG. 12A.

FIG. 13 is a perspective view showing removal of the glass base from thestage.

FIG. 14 is a perspective view showing the stage from which the glassbase has been removed.

FIG. 15 is a cross-sectional view showing the stage from which the glassbase has been removed.

FIG. 16 is a cross-sectional view showing flexible light-emittingdevices detached from the stage.

FIG. 17 is a cross-sectional view showing another protection sheet boundto a plurality of light-emitting devices which are in contact with thestage.

FIG. 18 is a cross-sectional view showing a carrier sheet carrying aplurality of parts which are to be mounted to the plurality oflight-emitting devices.

FIG. 19A is a cross-sectional view illustrating a step of the flexiblelight-emitting device production method in an embodiment of the presentdisclosure.

FIG. 19B is a cross-sectional view illustrating a step of the flexiblelight-emitting device production method in an embodiment of the presentdisclosure.

FIG. 19C is a cross-sectional view illustrating a step of the flexiblelight-emitting device production method in an embodiment of the presentdisclosure.

FIG. 19D is a cross-sectional view illustrating a step of the flexiblelight-emitting device production method in an embodiment of the presentdisclosure.

FIG. 20 is an equivalent circuit diagram of a single sub-pixel in aflexible light-emitting device.

FIG. 21 is a perspective view of the multilayer stack in the middle ofthe production process.

FIG. 22A is a cross-sectional view schematically showing a configurationexample of a surface-emission light source 215 which is capable ofradiating lift-off light 216.

FIG. 22B is a top view schematically showing the configuration exampleof the surface-emission light source 215.

FIG. 23 is a cross-sectional view schematically showing asurface-emission light source 215 which includes a plurality of lightemitting diode devices 400 that are two-dimensionally arrayed.

FIG. 24 is a cross-sectional view showing a surface-emission lightsource 215 in which the in-plane number density of the light emittingdiode devices 400 is high as compared with the example shown in FIG. 22.

FIG. 25 is a diagram showing an array of light emitting diode devices400 arrayed in rows and columns.

FIG. 26A is a diagram schematically showing the upper surface of a linebeam light source 214 which includes a single column of light emittingdiode devices arrayed in Y-axis direction.

FIG. 26B is a cross-sectional view of a multilayer stack shown in FIG.26A taken along line B-B.

FIG. 26C is a diagram showing the moving direction of the line beamlight source relative to the multilayer stack.

FIG. 27A is a diagram schematically showing the upper surface of a linebeam light source 214 which includes a plurality of columns of lightemitting diode devices arrayed in Y-axis direction.

FIG. 27B is a cross-sectional view of the line beam light source shownin FIG. 27A taken along line B-B.

FIG. 27C is a diagram showing the moving direction of the line beamlight source relative to the multilayer stack.

FIG. 28 is a top view schematically showing an example of asurface-emission light source in which a large number of light emittingdiode devices are arrayed in a matrix.

DESCRIPTION OF EMBODIMENTS

An embodiment of a method and apparatus for producing a flexiblelight-emitting device of the present disclosure is described withreference to the drawings. Examples of the “light-emitting device”include displays and illumination devices. In the following description,unnecessarily detailed description will be omitted. For example,detailed description of well-known matter and repetitive description ofsubstantially identical elements will be omitted. This is for thepurpose of avoiding the following description from being unnecessarilyredundant and assisting those skilled in the art to easily understandthe description. The present inventors provide the attached drawings andthe following description for the purpose of assisting those skilled inthe art to fully understand the present disclosure. Providing thesedrawings and description does not intend to limit the subject matterrecited in the claims.

<Multilayer Stack>

See FIG. 1A and FIG. 1B. In a flexible light-emitting device productionmethod of the present embodiment, firstly, a multilayer stack 100illustrated in FIG. 1A and FIG. 1B is provided. FIG. 1A is a plan viewof the multilayer stack 100. FIG. 1B is a cross-sectional view of themultilayer stack 100 taken along line B-B of FIG. LA. In FIG. 1A andFIG. 1B, an XYZ coordinate system with X-axis, Y-axis and Z-axis, whichare perpendicular to one another, is shown for reference.

The multilayer stack 100 includes a glass base (motherboard or carrier)10, a plurality of functional layer regions 20 each including a TFTlayer 20A and a light-emitting device layer 20B, a synthetic resin film(hereinafter, simply referred to as “plastic film”) 30 provided betweenthe glass base 10 and the plurality of functional layer regions 20 andbound to the glass base 10, and a protection sheet 50 covering theplurality of functional layer regions 20. The multilayer stack 100further includes a gas barrier film 40 provided between the plurality offunctional layer regions 20 and the protection sheet 50 so as to coverthe entirety of the functional layer regions 20. The multilayer stack100 may include another unshown layer, such as a buffer layer.

In the present embodiment, the light-emitting device layer 20B includes,for example, a plurality of OLED devices which are two-dimensionallyarrayed. In the present disclosure, the “light-emitting device layer”refers to a two-dimensional array of light-emitting devices. Each of thelight-emitting devices is not limited to an OLED device but may be amicro LED device. In the present embodiment, a typical example of theflexible light-emitting device is a “flexible display” but may be a“flexible illumination device”.

The first surface 100 a of the multilayer stack 100 is defined by theglass base 10. The second surface 100 b of the multilayer stack 100 isdefined by the protection sheet 50. The glass base 10 and the protectionsheet 50 are materials temporarily used in the production process butare not constituents of a final flexible light-emitting device.

The plastic film 30 shown in the drawings includes a plurality offlexible substrate regions 30 d respectively supporting the plurality offunctional layer regions 20, and an intermediate region 30 i surroundingeach of the flexible substrate regions 30 d. The flexible substrateregions 30 d and the intermediate region 30 i are merely differentportions of a single continuous plastic film 30 and do not need to bephysically distinguished. In other words, parts of the plastic film 30lying immediately under respective ones of the functional layer regions20 are the flexible substrate regions 30 d, and the other part of theplastic film 30 is the intermediate region 30 i.

Each of the plurality of functional layer regions 20 is a constituent ofa final flexible light-emitting device (e.g., display panel). In otherwords, the multilayer stack 100 has such a structure that a plurality offlexible light-emitting devices which are not yet divided from oneanother are supported by a single glass base 10. Each of the functionallayer regions 20 has such a shape that, for example, the thickness (sizein Z-axis direction) is several tens of micrometers, the length (size inX-axis direction) is about 12 cm, and the width (size in Y-axisdirection) is about 7 cm. These sizes can be set to arbitrary valuesaccording to the required largeness of the display screen or emissionsurface region. The shape in the XY plane of each of the functionallayer regions 20 is rectangular in the example illustrated in thedrawings but is not limited to this example. The shape in the XY planeof each of the functional layer regions 20 may include a square, apolygon, or a shape which includes a curve in the contour.

As shown in FIG. LA, the flexible substrate regions 30 d aretwo-dimensionally arrayed in rows and columns according to thearrangement of the flexible light-emitting devices. The intermediateregion 30 i consists of a plurality of stripes perpendicular to oneanother and forms a grid pattern. The width of the stripes is, forexample, about 1-4 mm. The flexible substrate region 30 d of the plasticfilm 30 functions as the “flexible substrate” in each flexiblelight-emitting device which is in the form of a final product.Meanwhile, the intermediate region 30 i of the plastic film 30 is not aconstituent of the final product.

In an embodiment of the present disclosure, the configuration of themultilayer stack 100 is not limited to the example illustrated in thedrawings. The number of functional layer regions 20 supported by asingle glass base 10 is arbitrary.

The size or proportion of each component illustrated in respectivedrawings is determined from the viewpoint of understandability. Theactual size or proportion is not necessarily reflected in the drawings.

The multilayer stack 100 which can be used in the production method ofthe present disclosure is not limited to the example illustrated in FIG.1A and FIG. 1B. FIG. 1C and FIG. 1D are cross-sectional views showingother examples of the multilayer stack 100. In the example illustratedFIG. 1C, the protection sheet 50 covers the entirety of the plastic film30 and extends outward beyond the plastic film 30. In the exampleillustrated FIG. 1D, the protection sheet 50 covers the entirety of theplastic film 30 and extends outward beyond the glass base 10. As will bedescribed later, after the glass base 10 is separated from themultilayer stack 100, the multilayer stack 100 is a thin flexiblesheet-like structure which has no rigidity. The protection sheet 50serves to protect the functional layer regions 20 from impact andabrasion when the functional layer regions 20 collide with or come intocontact with external apparatuses or instruments in the step ofdelaminating the glass base 10 and the steps after the delaminating.Since the protection sheet 50 is peeled off from the multilayer stack100 in the end, a typical example of the protection sheet 50 has alaminate structure which includes an adhesive layer of a relativelysmall adhesive force (a layer of an applied mold-releasing agent) overits surface. The more detailed description of the multilayer stack 100will be described later.

<Dividing Of Light-Emitting Devices>

According to the flexible light-emitting device production method of thepresent embodiment, after the step of providing the above-describedmultilayer stack 100, the step of dividing an intermediate region 30 iand respective ones of a plurality of flexible substrate regions 30 d ofthe plastic film 30 from one another is carried out.

FIG. 2 is a cross-sectional view schematically showing the positions fordividing the intermediate region 30 i and respective ones of theplurality of flexible substrate regions 30 d of the plastic film 30 fromone another. The positions of irradiation extend along the periphery ofeach of the flexible substrate regions 30 d. In FIG. 2, the positionsindicated by arrows are irradiated with a laser beam for cutting. Partof the multilayer stack 100 exclusive of the glass base 10 is cut into aplurality of light-emitting devices (e.g., displays) 1000 and theremaining unnecessary portions. By cutting, a gap of several tens ofmicrometers to several hundreds of micrometers is formed between each ofthe light-emitting devices 1000 and a portion surrounding thelight-emitting devices 1000. The cutting can also be realized by acutter which has a fixed blade or a rotary blade instead of the laserbeam irradiation. After the cutting, the light-emitting devices 1000 andthe remaining unnecessary portions are still bound to the glass base 10.

When the cutting is realized by a laser beam, the wavelength of thelaser beam may be in any of the infrared, visible and ultraviolet bands.From the viewpoint of reducing the effect of the cutting on the glassbase 10, the laser beam desirably has a wavelength in the range of greento ultraviolet. For example, when a Nd:YAG laser apparatus is used, thecutting can be carried out using a second harmonic wave (wavelength: 532nm) or a third harmonic wave (wavelength: 343 nm or 355 nm). In such acase, the laser power is adjusted to 1 to 3 watts, and the scanning rateis set to about 500 mm per second, so that the multilayer structuresupported by the glass base 10 can be cut (divided) into light-emittingdevices and unnecessary portions without damaging the glass base 10.

According to the embodiment of the present disclosure, the timing of theabove-described cutting is earlier than in the prior art. Since thecutting is carried out while the plastic film 30 is bound to the glassbase 10, alignment for the cutting can be made with high precision andaccuracy even if the gap between adjoining light-emitting devices 1000is narrow. Thus, the gap between adjoining light-emitting devices 1000can be shortened, and accordingly, useless portions which areunnecessary for a final product can be reduced. In the prior art, afterthe delaminating from the glass base 10, a polarizer, a heat radiationsheet, and/or an electromagnetic shield can be adhered to the plasticfilm 30 so as to cover the entirety of the surface (delaminated surface)of the plastic film 30. In such a case, the polarizer, the heatradiation sheet, and/or the electromagnetic shield are also divided bycutting into portions covering the light-emitting devices 1000 and theremaining unnecessary portions. The unnecessary portions are disposed ofas waste. On the other hand, according to the production method of thepresent disclosure, production of such waste can be suppressed as willbe described later.

<Lift-Off Light Irradiation>

After the intermediate region 30 i and respective ones of the pluralityof flexible substrate regions 30 d of the plastic film 30 are dividedfrom one another, the step of irradiating the interface between theflexible substrate regions 30 d of the plastic film 30 and the glassbase 10 with laser light is carried out using a delaminating apparatus.

FIG. 3A schematically shows a state in an unshown production apparatus(delaminating apparatus) immediately before the stage 212 supports themultilayer stack 100. In the present embodiment, the stage 212 is achuck stage which has a large number of pores in the surface forsuction. Details of the configuration of the chuck stage will bedescribed later. The multilayer stack 100 is arranges such that thesecond surface 100 b of the multilayer stack 100 faces the surface 212Sof the stage 212, and is supported by the stage 212.

FIG. 3B schematically shows a state where the stage 212 supports themultilayer stack 100. The arrangement of the stage 212 and themultilayer stack 100 is not limited to the example illustrated in thedrawing. For example, the multilayer stack 100 may be placed upside downsuch that the stage 212 is present under the multilayer stack 100.

In the example illustrated in FIG. 3B, the multilayer stack 100 is incontact with the surface 212S of the stage 212, and the stage 212 holdsthe multilayer stack 100 by suction.

Then, as shown in FIG. 3C, the interface between the plurality offlexible substrate regions 30 d of the plastic film 30 and the glassbase 10 is irradiated with lift-off light 216. FIG. 3C schematicallyillustrates irradiation of the interface between the glass base 10 andthe plastic film 30 of the multilayer stack 100 with the lift-off light216 in the shape of a line extending in a direction vertical to thesheet of the drawing. A part of the plastic film 30 at the interfacebetween the glass base 10 and the plastic film 30 absorbs the lift-offlight 216 and decomposes (disappears). By scanning the above-describedinterface with the lift-off light 216, the degree of binding of theplastic film 30 to the glass base 10 is reduced. The wavelength of thelift-off light 216 is typically in the ultraviolet band. The wavelengthof the lift-off light 216 is selected such that the lift-off light 216is hardly absorbed by the glass base 10 but is absorbed by the plasticfilm 30 as much as possible. The light absorption by the glass base 10is, for example, about 10% in the wavelength range of 343-355 nm but canincrease to 30-60% at 308 nm.

Hereinafter, irradiation with lift-off light in the present embodimentwill be described in detail.

<Lift-Off Light Irradiation Unit 1>

In the present embodiment, the delaminating apparatus includes a linebeam source for emitting the lift-off light 216. The line beam sourceincludes a laser apparatus and an optical system for shaping laser lightemitted from the laser apparatus into a line beam.

FIG. 4A is a perspective view schematically showing irradiation of themultilayer stack 100 with a line beam (lift-off light 216) emitted froma line beam source 214 of a delaminating apparatus 220. For the sake ofunderstandability, the stage 212, the multilayer stack 100 and the linebeam source 214 are shown as being spaced away from one another in theZ-axis direction of the drawing. During irradiation with the lift-offlight 216, the second surface 100 b of the multilayer stack 100 is incontact with the stage 212.

FIG. 4B schematically shows the position of the stage 212 duringirradiation with the lift-off light 216. Although not shown in FIG. 4B,the multilayer stack 100 is supported by the stage 212.

Examples of the laser apparatus that emits the lift-off light 216include gas laser apparatuses such as excimer laser, solid state laserapparatuses such as YAG laser, semiconductor laser devices, and othertypes of laser apparatuses. A XeCl excimer laser apparatus can generatelaser light at the wavelength of 308 nm. When yttrium orthovanadate(YVO₄) doped with neodymium (Nd) or YVO₄ doped with ytterbium (Yb) isused as a lasing medium, the wavelength of laser light (fundamentalwave) emitted from the lasing medium is about 1000 nm. Therefore, thefundamental wave can be converted by a wavelength converter to laserlight at the wavelength of 340-360 nm (third harmonic wave) before it isused. Laser light in the shape of a spot beam emitted from these laserapparatuses is combined with an optical system consisting of lenses andprisms for reshaping the light into the shape of a line beam, wherebylift-off light 216 in the shape of a line beam is produced.

A sacrificial layer (a thin layer of a metal or amorphous silicon) maybe provided at the interface between the plastic film 30 and the glassbase 10. From the viewpoint of suppressing generation of ashes, usinglaser light at the wavelength of 308 nm from the excimer laserapparatus, rather than laser light at the wavelength of 340-360 nm, ismore effective. Providing the sacrificial layer is highly effective insuppressing generation of ashes.

The irradiation with the lift-off light 216 can be carried out with thepower density (irradiance) of, for example, 250-300 mJ/cm². The lift-offlight 216 in the shape of a line beam has a size which can extend acrossthe glass base 10, i.e., a line length which exceeds the length of oneside of the glass base (long axis dimension, size in Y-axis direction ofFIG. 4B). The line length can be, for example, not less than 750 mm.Note that, however, if the line length of a line beam to be produced is1 m or more, the optical system for reshaping the laser light is too bigto construct and, accordingly, deterioration of the quality (uniformity)of the line beam is inevitable. Thus, usually, the longest possible linebeam has a length corresponding to the G6H substrate size (the shorterside of a 1800 mm×750 mm rectangle), i.e., a beam length up to about 750mm. Meanwhile, the line width of the lift-off light 216 (short axisdimension, size in X-axis direction of FIG. 4B) can be, for example,about 0.2 mm. These dimensions represent the size of the irradiationregion at the interface between the plastic film 30 and the glass base10. The lift-off light 216 can be emitted in the form of a pulsed orcontinuous wave. Irradiation with the pulsed wave can be carried out atthe frequency of, for example, about 200 times per seconds.

The position of irradiation with the lift-off light 216 moves relativeto the glass base 10 for scanning with the lift-off light 216. In thedelaminating apparatus 220, the multilayer stack 100 may be movablewhile the light source 214 from which the lift-off light is to beemitted and an optical unit (not shown) are stationary, and vice versa.In the present embodiment, irradiation with the lift-off light 216 iscarried out during a period where the stage 212 moves from the positionshown in FIG. 4B to the position shown in FIG. 4C. That is, scanningwith the lift-off light 216 is carried out by movement of the stage 212in the X-axis direction.

<Lift-Off Light Irradiation Unit 2>

In the above-described embodiment, the light source included in thelift-off light irradiation unit is a laser light source, although thelift-off light irradiation unit of the present disclosure is not limitedto this example. The lift-off light may be radiated from an incoherentlight source instead of a coherent light source such as laser lightsource. In the example described in the following paragraphs, theinterface between the plastic film and the glass base is irradiated withlift-off light radiated from an ultraviolet lamp.

FIG. 22A is a cross-sectional view schematically showing a configurationexample of a surface-emission light source 215 which is capable ofradiating lift-off light 216. FIG. 22B is a top view schematicallyshowing the configuration example of the surface-emission light source215.

The surface-emission light source 215 shown in the drawings includes aplurality of ultraviolet lamps 380 arrayed in a region which is oppositeto the multilayer stack 100 and a reflector 390 for reflectingultraviolet light radiated from each of the ultraviolet lamps 380. Theultraviolet lamps 380 can be, for example, high-pressure mercury-vaporlamps which are capable of radiating i-line at 365 nm. In the exampleillustrated in the drawings, the reflector 390 reflects ultravioletlight radiated from the ultraviolet lamps 380 such that the reflectedlight can be substantially collimated light. When the reflector 390 isformed by a cold mirror, the infrared part of the light radiated fromthe high-pressure mercury-vapor lamps is prevented from reaching themultilayer stack 100. An infrared cut-off filter may be provided betweenthe ultraviolet lamps 380 and the multilayer stack 100. By reducing orcutting off the infrared band which can be included in the lift-offlight 216, the temperature increase of the multilayer stack 100 byinfrared irradiation can be suppressed or prevented.

The irradiation energy of the lift-off light which is necessary fordelamination of the plastic film 30 is in the range of, for example, notless than 100 mJ/cm² and not more than 300 mJ/cm². The light source suchas the ultraviolet lamps 380 (incoherent light source) usually has asmall irradiation intensity per unit area as compared with thepreviously-described laser light source. Therefore, a sufficientirradiation energy can be achieved by increasing the duration oflift-off light irradiation as compared with a case where a laser lightsource is used.

The surface-emission light source 215 shown in FIG. 22A and FIG. 22B canform lift-off light 216 which spreads in the shape of a plane.Therefore, the duration of the irradiation at respective positions canbe increased as compared with scanning with a line beam.

In the example of FIG. 22A, the lift-off light 216 is collimated lightformed by the reflector 390, although the embodiments of the presentdisclosure are not limited to this example. Light radiated from each ofthe ultraviolet lamps 380 may be converged using the reflector 390 andan unshown lens into the shape of a line whose width is about 1-3 mm.When the multilayer stack 100 is irradiated with the lift-off light 216in the shape of such stripes, the entire surface of the multilayer stack100 can be irradiated with the lift-off light 216 by shifting therelative position of the surface-emission light source 215 with respectto the multilayer stack 100.

When the irradiation intensity of the ultraviolet light radiated fromthe ultraviolet lamps 380 is high, the entire surface of the multilayerstack 100 can also be irradiated with the lift-off light 216 by scanningwith the use of a single or several ultraviolet lamps 380. Even if theirradiation intensity of the ultraviolet light radiated from theultraviolet lamps 380 is not high, reducing the scanning speed enablesthe entire surface of the multilayer stack 100 to be irradiated with thelift-off light 216 by scanning with the use of a single or severalultraviolet lamps 380. Note that, however, due to restrictions on thelamp length of the ultraviolet lamps 380, it is difficult to apply theultraviolet lamps 380 to G8 substrates (2400 mm×2200 mm) or hugesubstrates of still larger sizes.

<Lift-Off Light Irradiation Unit 3>

In the example described in the following paragraphs, the interfacebetween the plastic film and the glass base is irradiated with lift-offlight radiated from an incoherent light source which includes aplurality of light emitting diode devices.

The light source used for radiating the lift-off light can be aplurality of light emitting diode (UV-LED) devices which are capable ofradiating ultraviolet light. Each of such light emitting diode deviceshas the size of, for example, 3.5 mm (longitudinal)×3.5 mm(transverse)×1.2 mm (thickness). The plurality of light emitting diodedevices can be arrayed in a single line or in a plurality of lines. Aspreviously described, in reshaping laser light in the shape of a spotbeam emitted from a conventional excimer laser or YAG laser into theshape of a line beam using an optical system including lenses andprisms, it is difficult to realize a line length of 1 m or more due tothe production cost of the optical system and increase in nonuniformityof the line beam after the reshaping of the laser light. Even if theultraviolet lamp is used, an unlimited line length cannot be realizedbecause the lamp length of the ultraviolet lamp has a limit. However,when a plurality of light sources are arrayed which are capable ofradiating ultraviolet light as in the present embodiment, the linelength of the lift-off light in the shape of a line beam can easily be 1m or more, and the irradiation unit is applicable to G8-size substrates(2400 mm×2200 mm) or huge substrates of still larger sizes.

FIG. 23 is a cross-sectional view schematically showing asurface-emission light source 215 which includes a plurality of lightemitting diode devices 400 that are two-dimensionally arrayed. Lightradiated from each of the light emitting diode devices 400 divergesaround the Z-axis direction at the center. This light represents thedistribution (directivity) of the relative radiation intensity whichdepends on the radiation angle θ that is the gradient from the Z-axis.In one example, the relative radiation intensity of the light emittingdiode devices can be about 75% at θ=45°, and about 50% at θ=65°. Thedirectivity of the light emitting diode devices can be adjusted byproviding a lens and/or reflector. Also in this case, bytwo-dimensionally arraying a large number of light emitting diodedevices 400, the irradiation unit is applicable to huge substratesalthough it is impossible in a conventional light source (a combinationof a laser light source and an optical system, or an ultraviolet lamp).

Commercially-available light emitting diode devices are capable ofradiating ultraviolet light at 365 nm with the power of 1450 milliwattson the driving conditions that, for example, the electric voltage is3.85 volts and the electric current is 1000 milliamperes.

FIG. 24 is a cross-sectional view showing a surface-emission lightsource 215 in which the in-plane number density of the light emittingdiode devices 400 is high as compared with the example shown in FIG. 23.As the in-plane number density of the light emitting diode devices 400increases, the irradiation intensity can increase.

FIG. 25 is a diagram showing an array of light emitting diode devices400 arrayed in rows and columns. The interval (array pitch) P betweenadjoining light emitting diode devices 400 is selected such that theirradiation intensity exceeds a level necessary for delamination acrossthe entirety of the interface between the plastic film and the glassbase.

<Lift-Off Light Irradiation Unit 4>

The emission intensity of the light emitting diode device is controlledby adjusting the magnitude of the driving current. Therefore, in aone-dimensional or two-dimensional array of light emitting diodedevices, by modulating the driving current flowing through each of thelight emitting diode devices, the irradiation intensity of the lift-offlight can be temporally and/or spatially modulated.

The array pitch of the light emitting diode devices is in the range of,for example, not less than 3 mm and not more than 10 mm. The lightradiated from the light emitting diode devices is incoherent(non-coherent) light, which is different from laser light. Thewavelength of the light radiated from the light emitting diode devicesis in the range of, for example, not less than 300 nm and not more than380 nm.

An example of a line beam light source in which a plurality of lightemitting diode devices are arrayed is described with reference to FIG.26A, FIG. 26B and FIG. 26C.

FIG. 26A schematically shows the upper surface of a line beam lightsource 214 which includes a plurality of light emitting diode devices400 arrayed in Y-axis direction. FIG. 26B is a cross-sectional view ofthe line beam light source 214 shown in FIG. 26A taken along line B-B.FIG. 26B also shows a multilayer stack 100. FIG. 26C is a diagramshowing the moving direction of the line beam light source 214 relativeto the multilayer stack 100.

In this example, the ultraviolet light radiated from the light emittingdiode devices 400 travels through a cylindrical lens 410 and enters theglass base 10 of the multilayer stack 100 in order to increase theirradiation energy per unit area (irradiation intensity expressed injoule/cm²). Since the ultraviolet light is focused in X-axis direction,the width (the size in X-axis direction) of the irradiation region inthe interface at which delamination is to occur (delamination plane) canbe decreased to, for example, about 0.2 mm or smaller. Since thecylindrical lens 410 does not focus the light in X-axis direction, thesize in Y-axis direction of the irradiation region is not shortened.

The irradiation intensity of the lift-off light can be increased bydecreasing the array pitch of the light emitting diode devices 400 suchthat the number density of the light emitting diode devices 400increases. For example, when each of the light emitting diode devices400 has the above-described size, several tens of light emitting diodedevices 400 or 100 or more light emitting diode devices 400 may bearrayed with the intervals of 3.5 mm to 10 mm (array pitch: the distancebetween the centers of adjoining light sources). When smaller lightemitting diode devices 400 are used, they can be arrayed with theintervals of, for example, 2.0 mm to 10 mm. The array pitch of the lightemitting diode devices 400 is preferably not more than 5 mm.

By moving the line beam light source 214 relative to the multilayerstack 100 as shown in FIG. 26C, the entire surface of the multilayerstack 100 can be irradiated with the lift-off light.

To increase the irradiation intensity of the line beam light source 214,the light emitting diode devices 400 may be arrayed in a plurality ofcolumns.

FIG. 27A schematically shows the upper surface of the line beam lightsource 214 which includes a plurality of columns of light emitting diodedevices 400 arrayed in Y-axis direction. FIG. 27B is a cross-sectionalview of the line beam light source 214 shown in FIG. 27A taken alongline B-B. FIG. 27B also shows the multilayer stack 100. FIG. 27C is adiagram showing the moving direction of the line beam light source 214relative to the multilayer stack 100.

In this example, the line beam light source 214 includes five columns oflight emitting diode devices 400 each extending in Y-axis direction. Thepositions in Y-axis direction of the five columns of light emittingdiode devices 400 are different from one another. The positions of thelight emitting diode columns are shifted by P/5 in Y-axis directionbetween adjoining columns where P is the array pitch. By moving the linebeam light source 214 relative to the multilayer stack 100 as shown inFIG. 27C, the entire surface of the multilayer stack 100 can beirradiated with the lift-off light.

The irradiation with the lift-off light may be carried out while theplurality of light sources are kept stationary relative to themultilayer stack 100.

FIG. 28 is a top view schematically showing an example of asurface-emission light source 215 in which a large number of lightemitting diode devices 400 are arrayed in a matrix. The number of lightemitting diodes arrayed vertically and horizontally only needs to bearbitrarily set according to the size of the substrate used. In thiscase, a delaminating apparatus applicable to G8-size substrates or hugesubstrates of still larger sizes can be realized. The plane to bedelaminated may be divided into a plurality of regions, and each of theregions may be irradiated with a flash of the lift-off light in the sameway as sequential exposure with the use of a stepper.

When the irradiation with the lift-off light is carried out while boththe multilayer stack 100 and the surface-emission light source 215 arekept stationary, a precise driving unit for light scanning is notnecessary. When the irradiation with the lift-off light is carried outwhile the multilayer stack 100 is moved relative to a stationary linebeam light source (FIG. 4A through FIG. 4C), an area which is at leasttwice the area of the multilayer stack 100 is necessary for the movementof the multilayer stack 100. However, when the surface-emission lightsource 215 is used, an extra area for the movement of the multilayerstack 100 is not necessary, and the area for installing the apparatuswill advantageously be halved.

Thus, using light emitting diode devices enables irradiation with thelift-off light at a lower cost with the use of a large number of lightsources rather than using semiconductor laser devices, which arerelatively expensive. Further, the duration of radiation of the lift-offlight from each of the light emitting diode devices can be easilyincreased. Therefore, even if the optical power of each of the lightemitting diode devices is small, the irradiation energy required fordelamination can be achieved by adjusting the irradiation duration.Furthermore, since laser light is not used, it is also advantageous fromthe viewpoint of safety for human eyes (eye-safe), and designing andoperation of the apparatus are easier.

<Lift-Off>

FIG. 5A illustrates a state where the multilayer stack 100 is in contactwith the stage 212 after irradiation with the lift-off light. While thisstate is maintained, the distance from the stage 212 to the glass base10 is increased. At this point in time, the stage 212 of the presentembodiment holds a light-emitting device portion of the multilayer stack100. At this point in time, a part of the intermediate region 30 ilocated at an end of the plastic film 30 may be secured to the glassbase 10 using an unshown pin or jig. The securing positions can be, forexample, at the four corners of the plastic film 30.

An unshown actuator holds the glass base 10 and moves the entirety ofthe glass base 10 in the direction of arrow L, thereby carrying outdelaminating (lift-off). The glass base 10 can be moved together with anunshown chuck stage while being adhered by suction to the chuck stage.The direction of movement of the glass base 10 does not need to bevertical, but may be diagonal, to the first surface 100 a of themultilayer stack 100. The movement of the glass base 10 does not need tobe linear but may be rotational. Alternatively, the stage 212 may bemoved upward in the drawing while the glass base 10 is secured by anunshown holder or another stage.

FIG. 5B is a cross-sectional view showing the thus-separated firstportion 110 and second portion 120 of the multilayer stack 100. FIG. 6is a perspective view showing the second portion 120 of the multilayerstack 100. The first portion 110 of the multilayer stack 100 includes aplurality of light-emitting devices 1000 which are in contact with thestage 212. The respective light-emitting devices 1000 include thefunctional layer regions 20 and the plurality of flexible substrateregions 30 d of the plastic film 30. Meanwhile, the second portion 120of the multilayer stack 100 includes the glass base 10 and theintermediate region 30 i of the plastic film 30.

In the example of FIG. 6, both the irradiation process with the lift-offlight and the delaminating process are carried out using thedelaminating apparatus 220 that includes the stage 212. The embodimentof the present disclosure is not limited to this example. Theirradiation process with the lift-off light may be carried out using alift-off light irradiation unit which includes a stage other than thestage 212, while the delaminating process is carried out using thedelaminating apparatus that includes the stage 212. In this case, afterirradiation with the lift-off light, it is necessary to transfer themultilayer stack 100 from the stage of the irradiation unit to the stage212. When the same stage is used for carrying out both the irradiationprocess with the lift-off light and the delaminating process, the stepof transferring the multilayer stack between the stages can be omitted.

As described above, in the present embodiment, the step of separatingthe multilayer stack 100 into the first portion 110 and the secondportion 120 is carried out while the stage 212 holds the second surface100 b of the multilayer stack 100 by suction. The essence of thisseparation step resides in that an unnecessary part of the multilayerstack 100 which is not a constituent of the light-emitting device 1000separates together with the glass base 10 from the stage 212. In thepresent embodiment, the cutting step illustrated in FIG. 2, i.e., thestep of cutting a part of the multilayer stack 100 exclusive of theglass base 10 into the plurality of light-emitting devices 1000 and theremaining unnecessary portions, is carried out before irradiation withthe lift-off light. Carrying out the cutting step before the lift-offlight irradiation step is effective in realizing the separationillustrated in FIG. 5B and FIG. 6.

In the present embodiment, the stage 212 plays an important role in theabove-described “separation”. Hereinafter, a configuration example ofthe stage 212 which can be suitably used in the present embodiment isdescribed.

<Configuration Example 1 of Stage>

FIG. 7 is a perspective view schematically showing a surface of thestage 212 in this example. FIG. 8 is a plan view schematically showingthe surface of the stage 212.

The stage 212 shown in the drawings includes a plurality of firstregions 300A which are to respectively face a plurality oflight-emitting devices 1000 (not shown) and a second region 300B whichis to face the intermediate region 30 i of the plastic film 30. Thesuction in the first regions 300A is greater than the suction in thesecond region 300B.

FIG. 9A is a schematic diagram enlargedly showing a portion in thevicinity of the boundary between the first region 300A and the secondregion 300B. FIG. 9B is a cross-sectional view taken along line B-B ofFIG. 9A. In this example, as shown in FIG. 9B, the stage 212 includes aporous front plate 222, a rear plate 224 which is parallel to the frontplate 222, a space 226 formed between these plates, and a suction sheet300 placed on the front plate 222. The space 226 is connected with asuction unit (not shown), such as a pump. During operation, the suctionunit makes the space 226 have a negative pressure, so that external airflows into the space 226 via a large number of voids of the porous frontplate 222 and openings (through holes 300H) of the suction sheet 300.Therefore, an object which is in contact with the suction sheet 300 issucked by the stage 212 and hence adhered by suction to the stage 212.

The porous front plate 222 can be made of various porous materials. Theporosity of the porous material is in the range of, for example, notless than 20% and not more than 60%. The average pore diameter is in therange of, for example, not less than 5 μm and not more than 600 μm. Anexample of the porous material is a sintered metallic or ceramic mass ora resin. The thickness of the porous material that forms the front plate222 is in the range of, for example, not less than 1 mm and not morethan 50 mm.

The suction sheet 300 has a plurality of through holes 300H as shown inFIG. 9A and FIG. 9B. The aperture ratio of the through holes 300H isdifferent between the first region 300A which is in contact with thelight-emitting device 1000 and the second region 300B which is to facethe intermediate region 30 i of the plastic film 30. The “apertureratio” of the suction sheet 300 refers to the area proportion of aregion (opening) in which the porous front plate 222 is exposed suchthat the suction function can be performed in the surface of the stage212.

The suction sheet 300 can be made of various materials such as, forexample, PET (polyethylene terephthalate), PVC (polyvinyl chloride), PP(polypropylene), fluoric resins (e.g., Polyflon), polyimide (PI), PC(polycarbonate), ABS resins. Alternatively, the suction sheet 300 may bemade of woven fabric, nonwoven fabric, a porous film, or the like. Thethickness of the suction sheet 300 can be, for example, about 0.05-3.0mm.

The surface of the porous front plate 222 can achieve generally uniformsucking force. When the suction sheet 300 is placed, the suction differsbetween the first region 300A and the second region 300B. A region ofthe surface of the front plate 222 which is covered with unopenedportions of the suction sheet 300 is incapable of sucking air and hencedoes not create suction. The suction sheet 300 can be used while it isadhered by suction to the porous front plate 222. The method of securingthe suction sheet 300 to the surface of the front plate 222 is notlimited to suction. The suction sheet 300 may be secured to the frontplate 222 or the stage 212 via an adhesive layer or a jig.

Using the suction sheet 300 in combination with an existing chuck stageeasily allows various designs of the multilayer stack 100. For example,when the shape, dimensions, number or arrangement pattern of thelight-emitting devices 1000 is changed, the suction sheet is replaced byanother suction sheet which is suitable to this change, whereby thein-plane distribution of the suction of the stage 212 can be easilychanged. In other words, it is only necessary to replace the suctionsheet 300 without changing the entirety of the stage 212.

In the present embodiment, the in-plane number density (hereinafter,simply referred to as “density”) of the through holes 300H in the firstregion 300A of the suction sheet 300 is higher than the density of thethrough holes 300H in the second region 300B. In other words, theaperture ratio of the first region 300A is higher than the apertureratio of the second region 300B. Therefore, the suction (sucking force)in the second region 300B is smaller than the suction in the firstregion 300A. The density of the through holes in the second region 300Bis about 0-50%, preferably about 0-30%, of the density of the throughholes 300H in the first region 300A. In one embodiment, the density ofthe through holes 300H in the second region 300B may be 0/cm².

The method of varying the suction between the first region 300A and thesecond region 300B is not limited to making difference in density of thethrough holes 300H in the suction sheet 300. By making difference insize and/or shape of the through holes 300H, difference can be made inaperture ratio, whereby the suction can be adjusted. Further, by makingthe thickness of the second region 300B of the suction sheet 300 smallerthan the thickness of the first region 300A, a gap may be formed betweenthe multilayer stack 100 and the second region 300B when the multilayerstack 100 is in contact with the first region 300A. Due to the presenceof such a gap, the suction in the second region 300B can be decreased.

By using the stage 212 which has the above-described configuration, inthe state shown in FIG. 5A, a plurality of flexible substrate regions 30d of the plastic film 30 which are in contact with the first regions300A of the stage 212 can respectively be adhered by suction to thefirst regions 300A of the stage 212. Meanwhile, the suction between theintermediate region 30 i of the plastic film 30 and the second region300B of the stage 212 is not strong. The intermediate region 30 i of theplastic film 30 is rather attached to the glass base 10. While theinterface between the intermediate region 30 i of the plastic film 30and the glass base 10 is irradiated with lift-off light, theintermediate region 30 i of the plastic film 30 can be kept attached tothe glass base 10 due to intermolecular forces, such as van der Waalsforce. Further, as previously described, when a part of the intermediateregion 30 i at an end of the plastic film 30 is secured to the glassbase 10 using a pin or jig, the entirety of the intermediate region 30 ican easily be kept on the glass base 10.

Further, in irradiating with lift-off light, the irradiation intensityof the lift-off light may be decreased for at least part of theintermediate region 30 i of the plastic film 30. If the irradiationintensity of the lift-off light is below a level required fordelamination, that part of the intermediate region 30 i of the plasticfilm 30 remains bound to the glass base 10. Thus, the intermediateregion 30 i of the plastic film 30 can easily be kept on the glass base10.

If the distance from the stage 212 to the glass base 10 is increasedwhile the stage 212 holds the second surface 100 b of the multilayerstack 100 by suction, the unnecessary portions of the multilayer stack100 can be separated together with the glass base 10 from thelight-emitting devices 1000. The unnecessary portions of the multilayerstack 100 are not adhered by suction to the second region 300B of thestage 212 and remain bound to the glass base 10.

In the configuration example described with reference to FIG. 9A andFIG. 9B, the shape and size of the first region 300A of the suctionsheet 300 which is in contact with the light-emitting device 1000 areidentical with the shape and size of the light-emitting device 1000,although the embodiment of the present disclosure is not limited to thisexample. If the suction in the first region 300A is sufficiently strong,the first region 300A only needs to face at least part of thelight-emitting device 1000, rather than the entirety of thelight-emitting device 1000.

FIG. 10 is a plan view showing a suction sheet 300 in anotherconfiguration example. The first regions 300A of the suction sheet 300can have an arbitrary shape and dimensions so long as the first regions300A hold by suction respective ones of the light-emitting devices 1000included in the multilayer stack 100 and do not come into contact withthe intermediate region 30 i of the plastic film 30.

FIG. 11A is a schematic diagram enlargedly showing a portion in thevicinity of the boundary between the first region 212A and the secondregion 212B in another configuration example of the suction sheet 300.FIG. 11B is a cross-sectional view taken along line B-B of FIG. 11A. Inthis example, the first region 300A is defined by a large opening 300Pthrough which the surface 212S of the front plate 222 that is made of aporous material is exposed. Meanwhile, the second region 300B covers thesurface 212S of the front plate 222 that is made of a porous material,thereby performing the function of reducing the suction. In the exampleillustrated in the drawings, the second region 300B has the throughholes 300H, although the through holes 300H are not indispensable in thesecond region 300B.

<Configuration Example 2 of Stage>

FIG. 12A is a schematic diagram enlargedly showing a portion in thevicinity of the boundary between the first region 212A and the secondregion 212B in a stage 212 in which the front plate 222 is realized by aplate which has through holes, rather than a plate which is made of aporous material. FIG. 12B is a cross-sectional view taken along line B-Bof FIG. 12A.

In this example, the density or aperture ratio of through holes 300H inthe first region 212A is higher than the density or aperture ratio ofthrough holes 300H in the second region 212B. Thus, the suction in thesecond region 212B is smaller than the suction in the first region 212A.

As described herein, the stage 212 may have a plurality of regions ofdifferent suctions.

<Steps After Delaminating>

FIG. 13 is a perspective view showing the first portion 110(light-emitting devices 1000) of the multilayer stack 100 adhered bysuction to the stage 212 and the second portion 120 (the glass base 10and objects bound thereto) at a position distant from the stage 212.Unnecessary portions of the multilayer stack 100 which are notconstituents of the light-emitting devices 1000 are bound to the glassbase 10.

FIG. 14 is a perspective view showing the first portion 110 of themultilayer stack 100 adhered by suction to the stage 212. The firstportion 110 of the multilayer stack 100 supported by the stage 212includes a plurality of light-emitting devices 1000 arrayed in rows andcolumns. In the example of FIG. 14, a part of the plastic film 30,specifically the surface (delaminated surface) 30S of the flexiblesubstrate regions 30 d, is exposed.

FIG. 15 is a cross-sectional view showing that the stage 212 holds thelight-emitting devices 1000 by suction. This cross section is parallelto the ZX plane. The direction of the Z-axis of FIG. 15 is opposite tothe direction of the Z-axis of FIG. 13 and FIG. 14.

Various processes can be sequentially or concurrently performed on theplurality of light-emitting devices 1000 which are in contact with thestage 212.

The “processes” to be performed on the light-emitting devices 1000 caninclude attaching a dielectric and/or electrically-conductive film toeach of the plurality of light-emitting devices 1000, cleaning oretching each of the plurality of light-emitting devices 1000, andmounting an optical part and/or an electronic part to each of theplurality of light-emitting devices 1000. Specifically, a part such as,for example, a polarizer, encapsulation film, touchscreen, heatradiation sheet, electromagnetic shield, driver integrated circuit, orthe like, can be mounted to the flexible substrate region 30 d of eachof the light-emitting devices 1000. The sheet-like part includes afunctional film which can add an optical, electrical or magneticfunction to the light-emitting devices 1000.

The plurality of light-emitting devices 1000 are supported by the stage212 such that the light-emitting devices 1000 are adhered by suction tothe stage 212. The various processes which are to be performed on eachof the light-emitting devices 1000 can be efficiently carried out.

The surface 30 s of the plastic film 30 delaminated from the glass base10 is active. Therefore, the surface 30 s may be covered with aprotection film or subjected to a surface treatment for conversion to ahydrophobic surface before various parts are mounted to the surface 30s.

FIG. 16 is a cross-sectional view schematically showing thelight-emitting devices 1000 detached from the stage 212 after thesheet-like part (functional film) 60 is mounted to the light-emittingdevices 1000.

According to the prior art, the plastic film is delaminated from theglass base before the light-emitting devices 1000 are divided from oneanother. Therefore, when a subsequent process is carried out, a largenumber of light-emitting devices 1000 are bound to a single plasticfilm. Thus, it is difficult to carry out an efficient process on each ofthe light-emitting devices 1000. When the light-emitting devices 1000are divided from one another after the sheet-like part is attached, aportion of the sheet-like part which is present in an intermediateregion between adjoining two of the light-emitting devices 1000 isuseless.

On the other hand, according to the embodiment of the presentdisclosure, a large number of light-emitting devices 1000 are stillorderly arrayed on the stage 212 after being delaminated from the glassbase 10. Therefore, various processes can be efficiently performed onthe light-emitting devices 1000 sequentially or concurrently.

After the step of separating the multilayer stack 100 into the firstportion 110 and the second portion 120, the step of adhering anotherprotection sheet (second protection sheet) 70 to the plurality oflight-emitting devices 1000 which are in contact with the stage 212 maybe further performed as shown in FIG. 17. The second protection sheet 70can perform the function of temporarily protecting the surface of theflexible substrate regions 30 d of the plastic film 30 delaminated fromthe glass base 10. The second protection sheet 70 can have the samelaminate structure as that of the previously-described protection sheet50. The protection sheet 50 can be referred to as “first protectionsheet 50”.

The second protection sheet 70 may be adhered to the plurality oflight-emitting devices 1000 after various processes which havepreviously been described are performed on the plurality oflight-emitting devices 1000 which are in contact with the stage 212.

When suction of the light-emitting devices 1000 by the stage 212 isstopped after the second protection sheet 70 is adhered, the pluralityof light-emitting devices 1000 which are bound to the second protectionsheet 70 can be detached from the stage 212. Thereafter, the secondprotection sheet can function as a carrier for the plurality oflight-emitting devices 1000. This is transfer of the light-emittingdevices 1000 from the stage 212 to the second protection sheet 70.Various processes may be sequentially or concurrently performed on theplurality of light-emitting devices 1000 which are bound to the secondprotection sheet 70.

FIG. 18 is a cross-sectional view showing a carrier sheet 90 carrying aplurality of parts (functional films) 80 which are to be mounted to theplurality of light-emitting devices 1000. By moving this carrier sheet90 in the direction of arrow U, the respective parts 80 can be attachedto the light-emitting devices 1000. The upper surface of the parts 80has an adhesive layer which is capable of strongly adhering to thelight-emitting devices 1000. Meanwhile, the adhesion between the carriersheet 90 and the parts 80 is relatively weak. Using such a carrier sheet90 enables a simultaneous “transfer” of the parts 80. Such a transfer isreadily realized because the plurality of light-emitting devices 1000are regularly arrayed on the stage 212 while the light-emitting devices1000 are supported by the stage 212.

Hereinafter, the configuration of the multilayer stack 100 before thedividing of FIG. 2 is described in more detail.

First, see FIG. 19A. FIG. 19A is a cross-sectional view showing theglass base 10 with the plastic film 30 provided on the surface of theglass base 10. The glass base 10 is a supporting substrate forprocesses. The thickness of the glass base 10 can be, for example, about0.3-0.7 mm.

In the present embodiment, the plastic film 30 is a polyimide filmhaving a thickness of, for example, not less than 5 μm and not more than100 μm. The polyimide film can be formed from a polyamide acid, which isa precursor of polyimide, or a polyimide solution. The polyimide filmmay be formed by forming a polyamide acid film on the surface of theglass base 10 and then thermally imidizing the polyamide acid film.Alternatively, the polyimide film may be formed by forming, on thesurface of the glass base 10, a film from a polyimide solution which isprepared by melting a polyimide or dissolving a polyimide in an organicsolvent. The polyimide solution can be obtained by dissolving a knownpolyimide in an arbitrary organic solvent. The polyimide solution isapplied to the surface 30 s of the glass base 10 and then dried, wherebya polyimide film can be formed.

In the case of a bottom emission type flexible display, it is preferredthat the polyimide film realizes high transmittance over the entirerange of visible light. The transparency of the polyimide film can berepresented by, for example, the total light transmittance in accordancewith JIS K7105-1981. The total light transmittance can be set to notless than 80% or not less than 85%. On the other hand, in the case of atop emission type flexible display, it is not affected by thetransmittance.

The plastic film 30 may be a film which is made of a synthetic resinother than polyimide. Note that, however, in the embodiment of thepresent disclosure, the process of forming a thin film transistorincludes a heat treatment at, for example, not less than 350° C., andtherefore, the plastic film 30 is made of a material which will not bedeteriorated by this heat treatment.

The plastic film 30 may be a multilayer structure including a pluralityof synthetic resin layers. In one form of the present embodiment, indelaminating a flexible display structure from the glass base 10, laserlift-off is carried out such that the plastic film 30 is irradiated withultraviolet lift-off light transmitted through the glass base 10. A partof the plastic film 30 at the interface with the glass base 10 needs toabsorb the ultraviolet lift-off light and decompose (disappear).Alternatively, for example, a sacrificial layer which is to absorblift-off light of a certain wavelength band and produce a gas may beprovided between the glass base 10 and the plastic film 30. In thiscase, the plastic film 30 can be easily delaminated from the glass base10 by irradiating the sacrificial layer with the lift-off light.Providing the sacrificial layer also achieves the effect of suppressinggeneration of ashes.

<Polishing>

When there is an object (target) which is to be polished away, such asparticles or protuberances, on the surface 30 x of the plastic film 30,the target may be polished away using a polisher such that the surfacebecomes flat. Detection of a foreign object, such as particles, can berealized by, for example, processing of an image obtained by an imagesensor. After the polishing process, a planarization process may beperformed on the surface 30 x of the plastic film 30. The planarizationprocess includes the step of forming a film which improves the flatness(planarization film) on the surface 30 x of the plastic film 30. Theplanarization film does not need to be made of a resin.

<Lower Gas Barrier Film>

Then, a gas barrier film may be formed on the plastic film 30. The gasbarrier film can have various structures. Examples of the gas barrierfilm include a silicon oxide film and a silicon nitride film. Otherexamples of the gas barrier film can include a multilayer film includingan organic material layer and an inorganic material layer. This gasbarrier film may be referred to as “lower gas barrier film” so as to bedistinguishable from a gas barrier film covering the functional layerregions 20, which will be described later. The gas barrier film coveringthe functional layer regions 20 can be referred to as “upper gas barrierfilm”.

<Functional Layer Region>

Hereinafter, the process of forming the functional layer regions 20,including the TFT layer 20A and the light-emitting device layer 20B, andthe upper gas barrier film 40 is described.

First, as shown in FIG. 19B, a plurality of functional layer regions 20are formed on a glass base 10. There is a plastic film 30 between theglass base 10 and the functional layer regions 20. The plastic film 30is bound to the glass base 10.

More specifically, the functional layer regions 20 include a TFT layer20A (lower layer) and a light-emitting device layer 20B (upper layer).The TFT layer 20A and the light-emitting device layer 20B aresequentially formed by a known method. When the light-emitting device isa display, the TFT layer 20A includes a circuit of a TFT array whichrealizes an active matrix. The light-emitting device layer 20B includesan array of light-emitting devices (OLED devices and/or micro LEDdevices), each of which can be driven independently.

The chip size of the micro LED devices is, for example, smaller than 100μm×100 μm. The micro LED devices can be made of different inorganicsemiconductor materials according to the color or wavelength of light tobe radiated. Identical semiconductor chips may include a plurality ofsemiconductor multilayer stacks of different compositions such thatlight of different colors, R (red), G (green) and B (blue), are radiatedfrom the respective semiconductor multilayer stacks. As well known inthe art, a semiconductor chip which radiates ultraviolet light or asemiconductor chip which radiates blue light may be combined withvarious phosphor materials such that light of R, G and B are radiated.

The thickness of the TFT layer 20A is, for example, about 4 μm. Thethickness of the light-emitting device layer 20B including the OLEDdevices is, for example, 1 μm. The thickness of the light-emittingdevice layer 20B including the micro LED devices can be, for example,not less than 10 μm.

FIG. 20 is a basic equivalent circuit diagram of a sub-pixel in adisplay which is an example of the light-emitting device. A single pixelof the display can consist of sub-pixels of different colors such as,for example, R, G, and B. The example illustrated in FIG. 20 includes aselection TFT element Tr1 a driving TFT element Tr2, a storage capacitorCH, and a light-emitting device EL. The selection TFT element Tr1 isconnected with a data line DL and a selection line SL. The data line DLis a line for transmitting data signals which define an image to bedisplayed. The data line DL is electrically coupled with the gate of thedriving TFT element Tr2 via the selection TFT element Tr1. The selectionline SL is a line for transmitting signals for controlling the ON/OFFstate of the selection TFT element Tr1. The driving TFT element Tr2controls the state of the electrical connection between a power line PLand the light-emitting device EL. When the driving TFT element Tr2 isON, an electric current flows from the power line PL to a ground line GLvia the light-emitting device EL. This electric current allows thelight-emitting device EL to emit light. Even when the selection TFTelement Tr1 is OFF, the storage capacitor CH maintains the ON state ofthe driving TFT element Tr2.

The TFT layer 20A includes a selection TFT element Tr1, a driving TFTelement Tr2, a data line DL, and a selection line SL. The light-emittingdevice layer 20B includes a light-emitting device EL. Before formationof the light-emitting device layer 20B, the upper surface of the TFTlayer 20A is planarized by an interlayer insulating film that covers theTFT array and various wires. A structure which supports thelight-emitting device layer 20B and which realizes active matrix drivingof the light-emitting device layer 20B is referred to as “backplane”.

The circuit elements and part of the lines shown in FIG. 20 can beincluded in any of the TFT layer 20A and the light-emitting device layer20B. The lines shown in FIG. 20 are connected with an unshown drivercircuit.

In the embodiment of the present disclosure, the TFT layer 20A and thelight-emitting device layer 20B can have various specificconfigurations. These configurations do not limit the presentdisclosure. The TFT element included in the TFT layer 20A may have abottom gate type configuration or may have a top gate typeconfiguration. Emission by the light-emitting device included in thelight-emitting device layer 20B may be of a bottom emission type or maybe of a top emission type. The specific configuration of thelight-emitting device is also arbitrary.

The material of a semiconductor layer which is a constituent of the TFTelement includes, for example, crystalline silicon, amorphous silicon,and oxide semiconductor. In the embodiment of the present disclosure,part of the process of forming the TFT layer 20A includes a heattreatment step at 350° C. or higher for the purpose of improving theperformance of the TFT element.

<Upper Gas Barrier Film>

After formation of the above-described functional layer, the entirety ofthe functional layer regions 20 is covered with a gas barrier film(upper gas barrier film) 40 as shown in FIG. 19C. A typical example ofthe upper gas barrier film 40 is a multilayer film including aninorganic material layer and an organic material layer. Elements such asan adhesive film, another functional layer which is a constituent of atouchscreen, polarizers, etc., may be provided between the upper gasbarrier film 40 and the functional layer regions 20 or in a layeroverlying the upper gas barrier film 40. Formation of the upper gasbarrier film 40 can be realized by a Thin Film Encapsulation (TFE)technique. When the light-emitting device layer 20B includes OLEDdevices, from the viewpoint of encapsulation reliability, the WVTR(Water Vapor Transmission Rate) of a thin film encapsulation structureis typically required to be not more than 1×10⁻⁴ g/m²/day. According tothe embodiment of the present disclosure, this criterion is met. Thethickness of the upper gas barrier film 40 is, for example, not morethan 2.0 μm.

FIG. 21 is a perspective view schematically showing the upper surfaceside of the multilayer stack 100 at a point in time when the upper gasbarrier film 40 is formed. A single multilayer stack 100 includes aplurality of light-emitting devices 1000 supported by the glass base 10.In the example illustrated in FIG. 21, a single multilayer stack 100includes a larger number of functional layer regions 20 than in theexample illustrated in FIG. 1A. As previously described, the number offunctional layer regions 20 supported by a single glass base 10 isarbitrary.

<Protection Sheet>

Next, refer to FIG. 19D. As shown in FIG. 19D, a protection sheet 50 isadhered to the upper surface of the multilayer stack 100. The protectionsheet 50 can be made of a material such as, for example, polyethyleneterephthalate (PET), polyvinyl chloride (PVC), or the like. Aspreviously described, a typical example of the protection sheet 50 has alaminate structure which includes a layer of an applied mold-releasingagent at the surface. The thickness of the protection sheet 50 can be,for example, not less than 50 μm and not more than 200 μm.

After the thus-formed multilayer stack 100 is provided, the productionmethod of the present disclosure can be carried out using theabove-described production apparatus (delaminating apparatus 220).

INDUSTRIAL APPLICABILITY

An embodiment of the present invention provides a novel flexiblelight-emitting device production method. A flexible light-emittingdevice is broadly applicable to smartphones, tablet computers, on-boarddisplays, and small-, medium- and large-sized television sets. Theflexible light-emitting device can also be used as an illuminationdevice.

REFERENCE SIGNS LIST

10 . . . glass base, 20 . . . functional layer region, 20A . . . TFTlayer, 203 . . . light-emitting device layer, 30 . . . plastic film, 40. . . gas barrier film, 50 . . . protection sheet, 100 . . . multilayerstack, 212 . . . stage, 220 . . . lift-off light irradiation unit(delaminating apparatus), 1000 . . . light-emitting device

1. An apparatus for producing a flexible light-emitting device,comprising: a stage for supporting a multilayer stack which has a firstsurface and a second surface, the multilayer stack including a glassbase which defines the first surface, a plurality of functional layerregions each including a TFT layer and a light-emitting device layer, asynthetic resin film provided between the glass base and the pluralityof functional layer regions and bound to the glass base, the syntheticresin film including a plurality of flexible substrate regionsrespectively supporting the plurality of functional layer regions and anintermediate region surrounding the plurality of flexible substrateregions, and a protection sheet which covers the plurality of functionallayer regions and which defines the second surface, the intermediateregion and respective ones of the plurality of flexible substrateregions of the synthetic resin film being divided from one another; alift-off light irradiation unit for irradiating with lift-off light aninterface between the plurality of flexible substrate regions of thesynthetic resin film and the glass base in the multilayer stacksupported by the stage; and an actuator for increasing a distance fromthe stage to the glass base while the stage holds the second surface ofthe multilayer stack by suction, thereby separating the multilayer stackinto a first portion and a second portion, wherein the first portion ofthe multilayer stack includes a plurality of light-emitting devicesadhered by suction to the stage, and the plurality of light-emittingdevices respectively include the plurality of functional layer regionsand include the plurality of flexible substrate regions of the syntheticresin film, and the second portion of the multilayer stack includes theglass base and the intermediate region of the synthetic resin film,wherein the lift-off light irradiation unit comprises an incoherentlight source for emitting the lift-off light, the incoherent lightsource being a surface-emission light source that comprises a pluralityof light emitting diode devices for emitting ultraviolet light and thelift-off light irradiation unit modulates a driving current flowingthrough each of the plurality of light emitting diode devices, therebytemporally and/or spatially modulating an irradiation intensity of thelift-off light.
 2. The apparatus of claim 1, wherein the surface of thestage includes a first region which is to face the plurality oflight-emitting devices and a second region which is to face theintermediate region of the synthetic resin film, and suction in thefirst region is greater than suction in the second region.
 3. Theapparatus of claim 1, wherein the stage includes a porous plate, and asuction sheet placed on the porous plate, the suction sheet having aplurality of openings, and the suction sheet includes a first regionwhich is to be in contact with the plurality of light-emitting devicesand a second region which is to face the intermediate region of thesynthetic resin film, an aperture ratio of the first region being higherthan an aperture ratio of the second region.
 4. A suction sheet for usein the apparatus of claim 3, comprising: a first region which is to bein contact with the plurality of light-emitting devices; and a secondregion which is to face the intermediate region of the synthetic resinfilm, wherein an aperture ratio of the first region is higher than anaperture ratio of the second region.